Fluid coupling apparatus, especially for a motor vehicle transmission

ABSTRACT

The invention proposes a fluid coupling apparatus in which the turbine wheel (28) is coupled in rotation to a shaft (34) through an interposed hub (36) made in one piece in sheet metal, which comprises an internally toothed sleeve portion (70) and an externally splined cylindrical skirt portion (66), for coupling together in rotation the hub (36) and an output member (60) of a lock-up clutch (16) of the fluid coupling apparatus (10).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fluid coupling apparatus, especiallyfor a motor vehicle transmission.

2. Description of the Related Art

The invention is concerned with an apparatus of the same type as thatdescribed and shown in the documents U.S. Pat. No. 4,875,562 andWO-A-94/07058.

In these known designs, such a fluid coupling apparatus is of the typecomprising a turbine wheel which is coupled to a turbine wheel hubconstituting a driven element, for rotation of the latter with theturbine wheel whereby to couple the latter in rotation with an outputshaft, together with an impulse wheel which is coupled to a drivingelement for rotation with the latter, and of the type comprising alockup clutch which is adapted to act between the driving element andthe driven element, and which comprises two coaxial parts which aremounted for movement of one with respect to the other against the actionof circumferentially acting springs, the said parts being an input partcomprising a piston, and an output part which is extended radiallyinwardly by a radial plate element for coupling it in rotation with thehub of the turbine wheel.

A locking clutch, usually called a "lock-up" clutch, for the fluidcoupling apparatus is interposed operatively between a driving elementand a driven element, and includes a torsion damper, a piston which ismounted for axial movement with respect to the driven element, and atleast one friction liner which is associated with the piston and whichis adapted to be gripped between the piston and a counter-piston.

In the document U.S. Pat. No. 4,875,562, the piston is so configured asto constitute the input part of the torsion damper, and it carries afriction liner which is arranged to come into contact with thetransverse wall of the housing of the fluid coupling apparatus, withthis wall constituting the counter piston.

The housing is a sealed casing which is filled with oil, and it isarranged to be coupled in rotation to a driving shaft.

The output part of the damper is fixed to the turbine wheel of the fluidcoupling apparatus.

The turbine wheel is fixed to a hub which is arranged to be coupled to adriven shaft for rotation of the latter with it.

Thus, the casing constitutes a driving element, while the hub of theturbine constitutes a driven element, and the lock-up clutch is adaptedto act between the casing and the turbine wheel so as to form a bridgingmeans between these latter.

In the document U.S. Pat. No. 4,875,562, the torsion damper includes thepiston which retains the springs (or resilient members) externally,together with a guide ring, which may be of divided form, which iscarried by the piston, and retains the springs on the inside by virtueof retaining lugs.

The input part thus consists of the piston and the guide ring, while theoutput part comprises an annular damper plate which is fixed to theturbine wheel.

The output damper plate has engagement lugs which penetrate between thecircumferencial ends of two consecutive springs so as to act on theselatter.

Each of these lugs penetrates radially between two engagement lugs whichare associated with the piston and the guide ring, respectively.

In the document WO-A-94/07058, the guide ring and the damper plate haveretaining portions for retaining the springs on the outside and on theinside respectively.

In addition, the damper plate and the guide ring have engagement lugsfor acting on the circumferencial ends of the springs.

Because of the retaining means it is possible, after the springs havebeen fitted by snap fitting of the damper plate behind snap-fittinglugs, to create a unitary sub-assembly which cannot be lost, which iscapable of being handled and transported, and which comprises the pistonand the torsion damper, this sub-assembly being then able to be fittedin position on the turbine hub.

In the designs proposed in the two said documents, the structure of theturbine hub and the ways used for fastening and/or coupling in rotationthe turbine wheel and/or the radial connecting plate element of theoutput part, are of particular complexity, and are expensive to carryout.

In the document U.S. Pat. No. 4,875,562, the hub of the turbine wheel isa heavy machined component which comprises a radially internal portionin the form of a sleeve, in which internal axial splines are machined.The hub includes a radial plate portion that extends radially outwardly,and on which the turbine wheel is fixed by a set of rivets in thevicinity of that portion of it which lies radially towards the inside,while its radially outward portion includes axial lugs which extendtowards the torsion damper. The output part of the lock-up clutch isalso guided on a machined cylindrical surface of the radially inner partof the hub of the turbine wheel.

In the document WO-A-94/07058, the output part includes a radial plateelement for coupling in rotation, which extends radially inwardlytowards an internally splined sleeve, at one end of which it is fittedby seaming, while the turbine wheel is fitted by riveting on a middleportion of the connecting plate portion, in the region of that part ofthe latter that lies radially towards the inside. In another design, thesplined sleeve includes a radial connecting plate portion which is madein one piece and machined, with the radial plate element that connectsthe output part and the turbine wheel for rotation together being fixedby riveting to its radially outer periphery.

SUMMARY OF THE INVENTION

All the designs which have just been described, of the turbine hub andthe means for fastening and/or coupling together in rotation the turbinewheel and the output part of the lock-up clutch damper, are veryexpensive, in that they call for numerous machining operations, whilethey require complex assembly operations which are difficult toautomate. In addition, the turbine wheel is heavy.

In order to overcome these drawbacks, the invention proposes a newdesign for a fluid coupling apparatus of the type described above,characterised in that the hub of the turbine wheel is made in one pieceand comprises:

a cylindrical skirt portion formed with external teeth, which is mountedfor axial sliding movement in a toothed central hole of the radial plateelement of the output part of the lock-up clutch;

a sleeve portion having internal splines and mounted on a splinedportion of the output shaft; and

an annular radial connecting plate element joining the splined skirtportion to the splined sleeve portion.

In accordance with other features of the invention:

the toothed skirt portion extends axially substantially in line with thesplined sleeve portion;

the connecting plate element joins an axial end of the splined sleeveportion to an axial end of the toothed skirt portion, and the connectingplate element lies substantially in a radial plane;

the hub of the turbine wheel is a sheet metal component;

the piston includes a flange for centring the piston with respect to thehub of the turbine wheel;

a centring piece is interposed between the centring flange of the pistonand the hub of the turbine wheel;

the centring piece includes a cylindrical internal wall portion mountedon the splined sleeved portion, a cylindrical external wall portion onwhich the centring flange is mounted, and a radial wall portionconnecting the cylindrical internal wall portion and external wallportion together;

the cylindrical external wall portion is joined to the radial connectingwall portion at a first axial end, and its second axial end is fixed tothe hub of the turbine wheel;

the second axial end of the cylindrical external wall portion of thecentring piece is extended axially outwardly by an annular fasteningflange which is adjacent to a radial surface, in facing relationshipwith it, of the connecting plate element of the hub of the turbinewheel, and which is fixed to that radial surface;

the centring piece is a sheet metal component;

the turbine wheel is fixed to the connecting plate element of the hub ofthe turbine wheel;

the turbine wheel is fixed on the radial surface of the connecting plateelement which is opposite to the radial surface to which the annularfastening flange is adjacent.

Further features and advantages of the invention will appear on areading of the following detailed description, for an understanding ofwhich, reference is made to the attached drawings in which;

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view an axial cross section of a fluid coupling apparatusmade in accordance with the feature;

FIG. 2 is a perspective view, shown partly cut away, of the hub of theturbine wheel in the fluid coupling apparatus of FIG. 1; and

FIG. 3 is a perspective view of the centring piece for centring thepiston on the hub of the turbine wheel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a fluid coupling apparatus 10, which includes, arranged ina common sealed housing 12 constituting an oil casing, a torqueconverter 14 and a lock-up clutch 16.

The casing 12 is a driving element, and it is adapted to be coupled inrotation to the crankshaft of the internal combustion engine of themotor vehicle, the transmission of which includes the fluid couplingapparatus.

The casing 12 is annular, and it comprises a first shell member 18having an annular wall 20 which is oriented generally transversely,together with a second shell member 22 which faces towards the firstshell member 18, and which is so configured as to define an impulsewheel 24 having vanes 26. The vanes 26 of the impulse wheel 24 are fixedto the internal face of the shell member 22. The shell members 18,22 arejoined to each other sealingly, in this example by welding at theirouter peripheries, while the annular transverse wall 20 carries acentring piece at its centre and, at its periphery, threaded portionsfor coupling it in rotation with the crankshaft (not shown).

The remainder of the torque converter comprises a turbine wheel 28having vanes 30 facing towards the vanes 26 of the impulse wheel 24 foroil circulation, together with a reaction wheel 32.

The turbine wheel 28 is coupled to a driven shaft 34, for rotation ofthe latter, through an interposed, central, turbine wheel hub 36, whilethe reaction wheel 32 is coupled to a sleeve 68 with a free wheel 38interposed. The sleeve 68 is fixed by means of a splined coupling to afixed shaft 40, also called a "reaction sleeve", for rotation with thelatter.

The fixed shaft 40 is of a tubular design to permit the passage throughit of the internal driven shaft 34, which is itself tubular so as toenable oil to pass through it. The driven shaft 34 is fixed to theturbine wheel hub 36, for rotation with the latter, in a manner whichwill be explained later herein.

The hub 36, which in this example is of metal, constitutes a drivenelement, and it is part of the lock-up clutch 16, being associated withthe output part of the latter. The second shell member 22 includes asleeve portion 42 which is inserted in a fixed bearing (not shown). Thelock-up clutch 16 is disposed axially between the annular transversewall 20 and the turbine wheel 28 of the casing 12.

The clutch 16 includes a torsion damper 44, a piston 46 which is mountedfor movement with respect to the driven element 36, and at least onefriction liner 48 which is associated with the piston 46, and which isadapted to be gripped axially between the piston 46 and a counter-pistonwhich consists of an annular portion 50, in facing relationship with it,of the transverse annular wall 20 of the first shell member 18constituting the driving element. The liner 48 is fixed to the piston46, or, in another version, to the wall 20.

The torsion damper comprises an input part 46, 52 and an output part 54,together with springs 55 (shown diagrammatically), which are interposedcircumferentially between the input part 46, 52 and the output part 54so as to couple these two parts together. The damper is arranged at theouter periphery of the sealed housing 1 2 and piston 46.

More precisely, the torsion damper 44 comprises two coaxial parts 46 and52-54, which are mounted for movement of one with respect to the otheragainst the action of the circumferentially acting springs 55, and whichconsist of an input part comprising the radial plate member 46 which isprovided with a guide ring 52, together with an output part 54 whichcomprises a damper plate 56, which in this example is integral with aradial plate element 60 to be described later herein.

The piston 46 has at its outer periphery an axially orientated annularskirt portion, and the guide ring 52 includes abutment portions forrespectively retaining in place, on the outer side in this example, thesprings 55, and for abutment of the latter, while the damper plate 56has abutment and retaining portions for providing abutment for thesprings 55 and for retaining the latter in place on the inner side. Theguide ring surrounds at least the greater part of the damper plate 56,and is secured to the piston 46 by riveting.

The abutment portions of the damper plate 56 are defined by stamped-out,sinuous abutment elements. In the guide ring 52, the abutment portionsconsist of two sets of lugs. For more detail, reference should be madeto the document WO-A-94/07058.

The output part 54 terminates radially on the inside in a radial plateelement 60 which is adapted to enable it to slide axially with respectto the hub 36 of the turbine wheel 28, while coupling it in rotationwith this hub.

For this purpose, the radial plate element 60, which is orientatedgenerally transversely, has a toothed central hole 62, which is splinedin this example.

The piston 46 is terminated radially on the inside by a cylindricalcentring flange 64 which projects towards the turbine wheel 28.

The hub 36, made in accordance with features of the invention, will nowbe described in greater detail.

The hub 36 is a one-piece component made from metal plate, for exampleby a roll-forming process.

The hub 36 includes an external cylindrical skirt portion 66, whichextends axially towards the wall 20, and which has a cylindricalperipheral surface which includes splines 68 sic! complementary to thosein the hole 62. This skirt portion 66 is therefore of toothed form, inaccordance with the invention.

The hub 36 also has a splined central sleeve portion 70, which extendsaxially towards the centring element of the wall 20, and which has acylindrical internal surface which includes splines 72, the latter beingarranged to enable the sleeve portion 70 to be fitted onto thecomplementary splined end portion 74 of the shaft 34.

The free end of the sleeve portion receives a sealing ring 170 toprovide sealing to the shaft 34.

The axial end 76 of the splined sleeved portion 70 that is nearest tothe turbine wheel 28 is joined to the axial end 78 of the skirt portion66 that is itself nearest to the turbine wheel 28, through an annularradial connecting plate element 80.

The connecting plate element 80 lies substantially in a radial plane,and, as can be seen in FIG. 1, the cylindrical skirt portion 66 extendsaxially in line with a portion of the splined sleeved portion 70, aroundthe latter, but over an axial length which is shorter that the axiallength of the splined sleeved portion 70. The hub 36 is thus U-shaped incross section, with two axial branches which extend towards the wall 20and which are of different lengths.

The sets of teeth, or splines, 68 and 72 of the splined skirt portion 66and splined sleeved portion 70 may be roll-formed.

As can be seen in FIG. 1, the turbine wheel 28 is coupled to the portionof the connecting plate element 80 that lies radially towards theoutside, by means of internal radial lugs 82 which are riveted on theplate element 80. In another version, the lugs 82 are replaced by acrown.

The turbine wheel 28 is thus coupled to its hub 36 for rotation with thelatter, as is the output part 54 through the splined hole 62.

The splined sleeve portion 70 defines a smooth external cylindricalperipheral surface 84 which constitutes a centring and abutment surfacefor a centring piece 86, which in this example is of metal, and which isinterposed between the hub 36 of the turbine wheel 28 and the centringflange 64 of the piston 46.

The centring piece 86 is a component of thin sheet metal, which isformed by a pressing and/or a roll-forming process.

The piece 86 includes an axially orientated cylindrical internal wallportion 88, which is mounted on the cylindrical surface 84, togetherwith an axially orientated cylindrical external wall portion 90 coaxialwith the cylindrical internal wall portion 88, and on which the centringflange 64 is mounted and centered.

The cylindrical internal wall portion 88 and external wall portion 90are joined together through an annular, radial connecting wall portion92, which joins together the axial terminal edges of the wall portions88 and 90 that lie closest to the transverse annular wall 20 of thefirst shell member 18.

The axial end 94 of the cylindrical external wall portion 90 that liesclosest to the radial connecting plate element 80 is extended radiallyoutwards by means of a fastening flange 96, which bears axially againstthe facing radial surface 81 of the connecting plate element 80, thissurface being opposite to the radial surface 79 on which the turbinewheel 28 is riveted.

Apart from the flange 96, the piece 86 has a U-shaped cross section, theaxial branches of which extend towards the plate element 80. Thesebranches are of different lengths, with the longer branch 90 beingdeformed locally so as to form a groove, for containing a sealing ringthat acts between the wall portion 90 and the flange 64 of the piston46.

The centring piece 86 is fastened on the hub 36 of the turbine wheel 28by riveting in the vicinity of the portion 98, extending radiallyoutwardly, of the fastening flange 96.

The hub 36 of the turbine wheel 28 constitutes a sub-assembly with thecentring piece 86 and with the turbine wheel 28.

Fitting and rotational coupling of this sub-assembly with the outputmember 54 of the lock-up clutch 16 and with the piston 46 isparticularly simple, in that it is sufficient to introduce,simultaneously, the splined cylindrical skirt portion 66 into the hole62, and the cylindrical external wall portion 90 into the centringflange 64 of the piston 46, without any associated riveting or sealingoperation.

The roll forming of the skirt portion 66 is preferably carried out usinga roll which co-operates with the internal wall surface of the skirtportion 66, so as to force the material of the latter into a die ringwhich is formed with splines and which is in contact with the externalsurface of the skirt portion 66. For the.sleeve portion 70 the method isreversed, the roll co-operating with the outer periphery of the sleeveportion 70 so as to force the material of the latter inwardly and causeit to penetrate into a die ring formed with splines.

It will be noted that the hub 36 and the centring piece 86 are fitted inhead-to-toe relationship with each other, and that in this example theyare press-formed from sheet metal.

The sub-assembly consisting of the hub 36 and centring piece 86 is thuslight in weight. It will be appreciated that the hub 36 can bestandardised, and that the centring piece 86 can be used as a componentfor adaptation purposes, according to the size of the radial plateelement 60.

In another version, the skirt portion 66 may of course be comb shaped,having at its free end axial teeth alternating with slots, its end 78being continuous. The hole 62 then has radial teeth alternating withslots, which mesh with the teeth and slots of the skirt portion 66,which is therefore toothed, as is the hole 62.

In a further version, the piece 86 may be secured to the hub 36 bywelding. Similarly the turbine wheel 28 may be fixed to the hub 36 bywelding.

The guide ring 52 is able to retain the springs, being the form of ahalf shell.

All of the arrangements described in the document WO-A-94/07058 may ofcourse be envisaged.

We claim:
 1. Fluid coupling apparatus (10) comprising a turbine wheel(28) which is coupled to a turbine wheel hub (36) constituting a drivenelement, for rotation of the hub (36) with the turbine wheel to therebycouple the turbine wheel in rotation with an output shaft (34), togetherwith an impulse wheel (24) which is coupled to a driving element forrotation with the impulse wheel, and comprising a lock-up clutch (18)which is adapted to act between the driving element and the drivenelement, and which comprises two coaxial parts (46, 52 to 54) which aremounted for movement of one with respect to the other against the actionof circumferentially acting springs (55), the parts being an input partcomprising a piston (46), and an output part (54) which is extendedradially inwardly by a radial plate element (60) for coupling the radialplate element in rotation with the hub (36) of the turbine wheel (28),wherein the hub (36) of the turbine wheel (28) is made in one piece andcomprises:a cylindrical skirt portion (66) formed with external teeth(68), which is mounted for axial sliding movement in a toothed centralhole (62) of the radial plate element (60) of the output part of thelook-up clutch (16); a sleeve portion (70) having internal splines (72)and mounted on a splined portion (74) of the output shaft (34); and anannular radial connecting plate element (80) joining the splined skirtportion (66) to the splined sleeve portion (70), wherein the hub (36) ofthe turbine wheel (28) is a sheet metal component.
 2. Fluid couplingapparatus according to claim 1, wherein the toothed skirt portion (66)extends axially.
 3. Fluid coupling apparatus according to claim 1,wherein the connecting plate element (80) joins an axial end (76) of thetoothed sleeve portion (70) to an axial end (78) of the splined skirtportion (661, and the connecting plate element (80) lies substantiallyin a radial plane.
 4. Fluid coupling apparatus according to claim 1,wherein the cylindrical skirt portion (66) of the turbine wheel hub (36)is splined.
 5. Fluid coupling apparatus according to claim 4, whereinthe said splined cylindrical skirt portion (66) is obtained by a rollforming process.
 6. Fluid coupling apparatus comprising a turbine wheel(28) which is coupled to a turbine wheel hub (36) constituting a drivenelement, for rotation of the hub (36) with the turbine wheel to therebycouple the turbine wheel in rotation with an output shaft (34), togetherwith an impulse wheel (24) which is coupled to a driving element forrotation with the impulse wheel, and comprising a lock-up clutch (18)which is adapted to act between the driving element and the drivenelement, and which comprises two coaxial parts (46, 52 to 54) which aremounted for movement of one with respect to the other against the actionof circumferentially acting springs (55), the parts being an input partcomprising a piston (46), and an output part (54) which is extendedradially inwardly by a radial plate element (60) for coupling the radialplate in rotation with the hub (36) of the turbine wheel (28), whereinthe hub (36) of the turbine wheel (28) is made in one piece andcomprises:a cylindrical skirt portion (66) formed with external teeth(68), which is mounted for axial sliding movement in a toothed centralhole (62) of the radial plate element (60) of the output part of thelook-up clutch (16); a sleeve portion (70) having internal splines (72)and mounted on a splined portion (74) of the output shaft (34); and anannular radial connecting plate element (80) joining the splined skirtportion (66) to the splined sleeve portion (70), said device furtherincludes a flange (64) for centring the piston (46) with respect to thehub (36) of the turbine wheel (28) and a centring piece (86) isinterposed between the centring flange (64) of the piston (46) and thehub (36) of the turbine wheel (28).
 7. Fluid coupling apparatusaccording to claim 6, wherein the centring piece (86) includes acylindrical internal wall portion (88) mounted on the splined sleevedportion (70, 84), a cylindrical external wall portion (90) on which thecentring flange (64) is mounted, and a radial wall portion (92)connecting the cylindrical internal wall portion (88) and external wallportion (90) together.
 8. Fluid coupling apparatus according to claim 7,wherein the cylindrical external wall portion (90) is joined to theradial connecting wall portion (92) at a first axial end, and a secondaxial end (94) of the cylindrical external wall is fixed to the hub (36)of the turbine wheel (28).
 9. Fluid coupling apparatus according toclaim 8, wherein the second axial end (94) of the cylindrical externalwall portion (90) of the centring piece (86) is extended axiallyoutwardly by an annular fastening flange (96) which is adjacent to aradial surface (81), in facing relationship with it, of the connectingplate element (80) of the hub (36) of the turbine wheel (28), and whichis fixed to that radial surface.
 10. Fluid coupling apparatus accordingto claim 9, wherein the turbine wheel (28) is fixed to the connectingplate element (80) of the hub (36) of the turbine wheel (28).
 11. Fluidcoupling apparatus according to claim 10, wherein the turbine wheel (28)is fixed on the radial surface (79) of the connecting plate element (80)which is opposite to the radial surface (81) to which the annularfastening flange (96) is adjacent.
 12. Fluid coupling apparatusaccording to claim 6, wherein the centring piece (86) is a sheet metalcomponent.